In the optical fiber distance measurement based on optical frequency domain reflectometer (OFDR), the nonlinear tuning effect of the light source directly affects the accuracy of the measurement distance, which makes the OFDR measurement result shift. By theoretically analyzing the relationship between the linearity of laser tuning and measurement distance, a method of distance correction is proposed in this paper. An auxiliary interferometer is used to measure the nonlinearity offset of the light source tuning, and the interpolation is directly performed in the signal frequency domain according to the offset. Experiments show that this method can eliminate the influence of the nonlinear tuning of the light source on the measurement distance, improve the accuracy and spatial resolution of the OFDR measurement distance effectively. Since the calculation is completed in a frequency sweep period, it's very efficiency.